1. Technical Field
This invention relates to a method for electrochemically processing articles, such as cylindrically shaped, hollow tubing articles, and more specifically, to methods and to apparatuses used for plating processes.
2. Background Information
One example of hollow articles requiring plating is tubing used in the aerospace field. The tubing is used for flowing fuel, lubricating fluid, hydraulic fluid and the like, typically in high-pressure applications. The tubing is relatively small in diameter (less than one inch) and is typically joined to a mating component using braze material. The tubing frequently receives a coating to provide a smooth surface. The coating is carefully applied because the coated tubing has controlled tolerances. The smooth surface and controlled tolerances ensure that capillary forces will urge the braze material to flow into a predetermined gap between the tubing and the component.
One approach for providing the coating uses a plating process having a large-scale bath and includes disposing many pieces of tubing in the bath. A large-scale plating bath may not efficiently use the plating solutions, increasing purchasing costs and increasing disposal costs of the environmentally sensitive waste. Depending on the location of the tubing in the bath, the tubing might receive a thicker than desired coating or a thinner then desired coating. In addition, a large-scale plating bath may well be located at a sit remote from the location at which the brazing processes are carried out.
Another approach for providing the coating is a brush plating process. The electrolytes used for brush plating have a higher metal content than electrolytes for conventional plating baths. Brush plating processes employ a carbon anode wrapped in a conductive pad. The conductive pad is soaked in the electrolyte. This is essential to achieve higher rates of plating deposition. A current is passed through the pad and to the article as the operator rubs the pad over the surface.
An advantage of the brush plating process is little waste and acceptable levels of time for work in process. However the process is labor-intensive and variations in technique from operator to operator increase the difficulty of precisely controlling the plating thickness. In addition, the operator must handle harsh chemicals during cleaning and etching and must hold and move the anode with a repetitive motion that causes fatigue and which might cause repetitive motion injuries.
Accordingly, scientists and engineers working under the direction of Applicants Assignee have sought to develop a plating process and apparatus for use with such processes that provide efficient use of solutions, efficient use of rinsing water and may be installed in local work areas.